Process for neutralizing and sweetening gasoline



Patented Aug. 29, 1933 UNITED STATES PROCESS FOR NEUTRALIZING ANDSWEETENIN G GASOLINE Hugh Harley Cannon, Los Angeles, Calif., as-

signor to Cannon-Prutzman Treating Proc esses, Ltd., Los Angeles,Calif., a corporation of California No Drawing. Application October 2,1929- Serial No. 396,903

6 Claims.

In a copending application Serial-No. 376,516,

filed July 8, 1929, I have described and claimed a process forsweetening gasoline in which the mercaptans are continuously removedfrom gasolines and pressure distillates by passing such oils through acontacting vessel containing a mixture of lime, litharge, diatomaceousearth and a minute quantity of caustic soda, such mixture being asubstantially dry powder.

10 In an application filed contemporaneously herewith, Serial No.396,900, filed October 2, 1929,

I have described and claimed a process for neutralizing acid treatedgasolines and similar oils by treating them with a fiuid magmacomposedof sodium hydroxid ground to a state of extreme subdivision inkerosene or a similar light oil vehicle, water being substantiallyexcluded.

I have discovered that these two processes may be somewhat modified andthen combined to produce a unitary process in which acid treatedgasoline or distillate containing mercaptan sulfur may be simultaneouslyneutralized and sweetened at a reduced cost.

In putting my invention into practice I take the following steps. Thegasoline (for example) is first treated with any desired quantity ofsulfuric acid in any preferred manner. I prefer to treat continuously asmy neutralization process is essentially continuous and continuous acidtreatment gives the most even and dependable yield of treated stock.

The acid sludge should then be removed as completely as possible,preferably down to the point where the total acidity does not exceed 20grams per barrel of oil, when calculated as sulfuric acid. This shouldnot be considered a limitation on the usefulness of my process as it isessential to any successful treatment with alkalis and particularlywhere neutralization is my dry reagent.

To the stream of desludged oil should then be added a sufiioientquantity of my sodium hydroxid reagent to completely neutralize theacidity and leave a very slight excess. This sodium hydroxid reagent ismade by very finely grinding dry commercial sodium hydroxid, to a pastyor fluent condition in a high grade kerosene or equivalent petroleumproduct which may be mixed in small 00 proportion with the gasolinewithout detriment to its qualities. Either at this stage or elseimmediately after the desludging operation I add to the gasoline asufficient quantity of a gasoline solution of sulfur to precipitate thelead from the lead mercaptide conducted with aqueous alkalis instead ofwith formed in the next stage of the operation. The quantity of sulfuradded at this stage may equal the quantity of sulfur contained in theoil in mercaptan form, if this can be conveniently determined, or thecorrectness of the proportion may be checked from time to time bytesting the efliuent sweetened oil, as will hereafter be dedescribed.

The neutralized gasoline, containing the correct proportion of sulfurfor sweetening and also retaining the neutralization reaction salts, isthen passed to and through the lead contactor. This is a vessel of anyconvenient size and shape, preferably a vertical cylinder having a conebottom and above this bottom a grid supports a wire mesh screen on whichthe lead powder may rest. The gasoline is pumped into this vessel at anypoint below the screen, rises through the lead pack, which it shouldkeep in gentle agitation, rises further through the empty upper portionof the vessel, where any suspended lead powder subsides, and overflowsthrough a vent situated near the top. From this vent the neutral sweetgasoline is pumped through any convenient type of filter press, equippedpreferably with cotton 30 cloths, from which it is pumped to storage.

- The lead contactor should be filled to about half its height (measuredabove the screen) with a lead reagent consisting of litharge,diatomaceous earth and a little caustic soda. I prefer to make thisreagent by dissolving in a little water one part by weight of commercialcaustic soda, stirring into thissolution thirty parts by weight ofcommercial powdered litharge, which produces a damp powder, and furtherincorporating five parts by weight of a high grade diatomaceous earth,which produces a substantially dry powder. The product consists ofpowdered litharge containing a little sodium plumbite and distended witha relatively large volume'of light porous earth. The proportions givenare suggestive only, it being possible to entirely omit the diatomaceousearth or to reduce or increase its proportion, and to quite materiallyalter the proportion of caustic soda, though it is not desirable to omitthis entirely.

The rationale of this process is as follows: The acidity of the gasolineis neutralized by the dry sodium hydroxid without danger ofemulsification or loss.- The excess of alkali which is requisite toproduce complete neutralization is carried forward and utilized in thesweetening process.

The small quantity of sodium plumbite in the lead contactors convertsthe mercaptans into lation of sodium sulfid and neutralization reactionproducts.

Any portion or" the sodium salts and any lead or earth which floats overfrom the contactors is caught in the filter which gives a pure brilliantgasoline, the filter cake being in condition to return to the contactorsat intervals.

When the lead reacts too slowly, for the reason above given, a materialproportion of the original quantity may be recovered by draining off thegasoline, washing until all the soluble as salts have been extractedwith hot water .(these being neutralization salts, sodium sulfid andsodium plumbite), blowing the mixture with air until substantially dryand mixing in a small quantity of sodium plumbite. It is not necessaryto oxidize the lead sulfid of which the mass is principally composed asit will begin to convert as soon as the cycle is reestablished. Nolead'is lost except the small quantity washed out as sodium plunibite.

The sulfur solution may conveniently be prepared oy percolating gasolinethrough a tower partly fill d with solid sulfur, separating anysuspended sulfur and placing the solution in V ,tanks. In these it maybe brought to any convenient standard by the addition of furtherquantitles of gasoline.

In order to keep the sulfur solution in correct proportion to the oil itis preferable to test the filter eifi nt rather than'to calculate theproper .13 proporti n of solution. If the filter eiliuent gives apositive reaction to the well known doctor test it is sour and thedosage of sulfur oil is insufficient. If it is negative to doctor andpositive to the copper strip test or, more sensitively, to the hutylmercaptan test, it is corrosive and the dosage of sulfur is too great.

The process above described will be found high- 1y economical ofreagents and particularly of oil.

a lo in itsapplication there need be o exposure of the 56 oil to air orcontact with water-rrom the time the oil enters the cid treater until itemerges from the filter asfinished sweetened gasoline. Losses due toevaporation, sludging emulsification and entrainment v are thereforealmost entirely v1 avoided, practically the only loss of raw materialbeing that due to the action of the acid, and even this is mat riallyreduced as t .ere need he no lossof color after the acid treatment andthe acid dosage may therefore be materially reduced.

The portion of the above process which refers to the sweetening of theoil may be separately applied by passing into the lead contactors an oilintermixed with finely comminuted solid sodium hydroxld, or even withoutsuch intermixture, in which latter case t is lead mass will functiononly until the sodium hydroxid contained therein is completely convertedinto lead sulfid.

The entire process ah ve described is preferably 1 carried out at normalatmospheric temperatures.

- I claim as my invention:

l. The method of sweetening oils containing iercaptans which comprises:adding to said oil sodium hydroxid in quantity exceeding finelycomminuted solid sodium hydroxid and sulfur in quantity sufficient forsweetening, and passing said liquid mixture through a substantially drypowdered mass comprising lead monoxid and sodium hydroxid, the additionof water being avoided.

2. The method of sweetening oils containing 'mercaptans which comprises:adding to said oil finely comminuted solid sodium hydroxid and sulfur inquantity suificient for sweetening, and passing said liquid mixturethrough a substantially dry powdered mass comprising lead monoxid,sodium hydroxid and a finely comminutedporous earthy material, theaddition of water being avoided.

3. The-method of neutralizing and sweetening acidified oils containingmercaptans which comprises; adding to said oil finely comminuted sodiumhydroxid in quantity exceeding that which corresponds to the acidity ofthe soil and also adding to said oil sulfur in quantity sufficient forsweetening, and contacting said liquid mixture with a substantially drypowdered mass comprising lead monoxid and sodium hydroxid, the additionof water being avoided.

4. The method of neutralizing and sweetening acidified oils containingmercaptans which comprises: adding to said oil finely comminuted thatwhich corresponds to the acidity of the soil and also adding to said oilsulfur in quantity sufficient for sweetening, and contacting said liquidmixture with a substantially dry powdered mass comprising lead inonoxid,sodium hydroxid and a finely comminuted porous earthy material, theaddition of water being avoided.

5. The continuous method of acid treating and sweetening oils containinginercaptans, which comprises: continuously treating said oil withsulfuric acid; continuously separating and withdrawing the major portionof the acid sludge formed by said treatment; adding to said acidifiedoil finely comminutod sodium hydroxid' in quantity sufiicient toslightly overneutralize the remaining acidity and adding to said oilsulfur in quantity sufdcient for sweetening; continuously contactingsaid liquid mixture with a substantially dry powdered mass comprisinglead monoxid and sodium hydroxid and filtering from the oil anysuspended solids, the aforesaid operations being performed substantiallyout of contact with air and addition of water being avoided throughout.

6. The continuous method of acid treating and sweetening oils containingmercaptans, which comprises: continuously treatingsaid oil with sulfuricacid; continuously separating and withdrawing the major portion of theacid sludge formed by said treatment; adding to said acidified oilfinely comminuted sodium hydroxid in quantity suficient to slightlyoverneutralize the remaining acidity and adding to said oil sulfur inquantity sufficient for sweetening; continuously contacting said liquidmixture with a substan-- tially dry powdered mass comprising leadmonoxid, sodium hydroxi'd and a finely comminuted porous earthymaterial, and filtering from the oil any suspended solids; the aforesaidoperations being performed substantially out of contact with air andaddition of water being avoided throughout. g

HUGH HARLEY CANNON.

